U.S. patent application number 15/881359 was filed with the patent office on 2018-05-31 for two-transformer three-phase dc-dc resonant converter.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Grover Victor Torrico-Bascope.
Application Number | 20180152112 15/881359 |
Document ID | / |
Family ID | 56404104 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180152112 |
Kind Code |
A1 |
Torrico-Bascope; Grover
Victor |
May 31, 2018 |
Two-Transformer Three-Phase DC-DC Resonant Converter
Abstract
A transformer circuit includes a first transformer, a second
transformer and an inductor, where a first terminal of the first
transformer is coupled to a first terminal of the second
transformer. The inductor is coupled between a second terminal of
the first transformer and a second terminal of the second
transformer.
Inventors: |
Torrico-Bascope; Grover Victor;
(Kista, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
|
CN |
|
|
Family ID: |
56404104 |
Appl. No.: |
15/881359 |
Filed: |
January 26, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/EP2016/066080 |
Jul 7, 2016 |
|
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15881359 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02M 2001/0058 20130101;
Y02B 70/1433 20130101; Y02P 80/112 20151101; Y02B 70/1491 20130101;
H01F 27/29 20130101; H01L 29/2003 20130101; H02M 1/083 20130101;
Y02P 80/10 20151101; H02M 3/33592 20130101; H02M 3/33584 20130101;
Y02B 70/10 20130101 |
International
Class: |
H02M 3/335 20060101
H02M003/335; H01F 27/29 20060101 H01F027/29 |
Claims
1. A transformer circuit, comprising: a first transformer; a second
transformer, wherein a first terminal of the first transformer is
coupled to a first terminal of the second transformer; and an
inductor coupled between a second terminal of the first transformer
and a second terminal of the second transformer.
2. The transformer circuit according to claim 1, further comprising
a primary side configured to receive a three-phase power input, and
wherein the primary side comprises: a first input node formed by
coupling the second terminal of the first transformer and a first
terminal of the inductor; a second input node formed by coupling
the first terminal of the first transformer and the first terminal
of the second transformer; and a third input node formed by
coupling the second terminal of the second transformer and a second
terminal of the inductor.
3. The transformer circuit according to claim 2, wherein the first
input node is configured to receive a first phase of the
three-phase power input, wherein the second input node is
configured to receive a second phase of the three-phase power
input, and wherein the third input node is configured to receive a
third phase of the three-phase power input.
4. The transformer circuit according to claim 2, wherein the
primary side of the transformer circuit is coupled to a resonant
tank circuit to receive the three-phase power input.
5. The transformer circuit according to claim 4, wherein the first
input node is coupled to a first branch of the resonant tank
circuit to receive a first phase of the three-phase power input,
wherein the second input node is coupled to a second branch of the
resonant tank circuit to receive a second phase of the three-phase
power input, and wherein the third input node is coupled to a third
branch of the resonant tank circuit to receive a third phase of the
three-phase power input.
6. The transformer circuit according to claim 1, further comprising
a secondary side configured to deliver a three-phase power output,
and wherein the secondary side comprises: a first output node
formed by a third terminal of the first transformer; a second
output node formed by coupling a fourth terminal of the first
transformer and a fourth terminal of the second transformer; and a
third output node formed by a third terminal of the second
transformer.
7. The transformer circuit according to claim 6, wherein the
secondary side is coupled to a. three-phase rectifier circuit to
deliver the three-phase power output, wherein the first output node
is coupled to a first branch of the three-phase rectifier circuit,
wherein the second output node is coupled to a second branch of the
three-phase rectifier circuit, and wherein the third output node is
coupled to a third branch of the three-phase rectifier circuit.
8. A resonant converter circuit, comprising: a resonant tank
circuit; and a transformer circuit coupled to the resonant tank
circuit, wherein the transformer circuit comprises: a first
transformer; a second transformer, wherein a first terminal of the
first transformer is coupled to a first terminal of the second
transformer; and an inductor coupled between a second terminal of
the first transformer and a second terminal of the second
transformer, and wherein the resonant tank circuit is coupled to a
primary side of the transformer circuit.
9. The resonant converter circuit according to claim 8, wherein the
resonant tank circuit comprises: a first branch coupled to a first
input node of the transformer circuit; a second branch coupled to a
second input node of the transformer circuit; and a third branch
coupled to a third input node of the transformer circuit.
10. The resonant converter circuit according to claim 9, wherein
the first branch is coupled between a first input node of the
resonant tank circuit and the first input node of the transformer
circuit, wherein the second branch is coupled between a second
input node of the resonant tank circuit and the second input node
of the transformer circuit, and wherein the third branch is coupled
between a third input node of the resonant tank circuit and the
third input node of the transformer circuit.
11. The resonant converter circuit according to claim 10, wherein
the first branch comprises a first branch inductor coupled in
series with a first branch capacitor, wherein a first end of the
first branch is coupled to the first input node of the transformer
circuit, wherein the second branch comprises a second branch
inductor coupled in series with a second branch capacitor, wherein
a first end of the second branch is coupled to the second input
node of the transformer circuit, wherein the third branch comprises
a third branch inductor coupled in series with a third branch
capacitor, and wherein a first end of the third branch is coupled
to the third input node of the transformer circuit.
12. A three-phase resonant direct current-direct current (DC-DC)
converter system, comprising: a primary side; a secondary side; and
a transformer circuit coupled between the primary side and the
secondary side, wherein the transformer circuit comprises: a first
transformer; a second transformer, wherein a first terminal of the
first transformer is coupled to a first terminal of the second
transformer; and an inductor coupled between a second terminal of
the first transformer and a second terminal of the second
transformer.
13. The three-phase resonant DC-DC converter system according to
claim 12, wherein the primary side comprises a DC voltage input
circuit configured to receive a DC input voltage, wherein a
resonant tank circuit is coupled to the transformer circuit to
provide a three-phase power input to the transformer circuit, and
wherein a switching circuit is coupled between the DC voltage input
circuit and the resonant tank circuit.
14. The three-phase DC-DC converter system according to claim 13,
wherein the secondary side comprises a three-phase rectification
circuit coupled between the transformer circuit and a DC voltage
output circuit, and wherein the three-phase rectification circuit
is configured to receive a three-phase power output signal from the
transformer circuit.
15. The three-phase DC-DC converter system according to claim 14,
wherein switches in the switching circuit and switches in the
three-phase rectification circuit comprise gallium-nitride (GaN)
transistors.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The application is a continuation of International Patent
Application No. PCT/EP2016/066080 filed on Jul. 7, 2016, which is
hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The aspects of the present disclosure relate generally to
power conversion apparatus and in particularly, to resonant direct
current (DC) to DC power converters.
BACKGROUND
[0003] Resonant DC to DC converters are considered to be attractive
power conversion solutions for the many benefits they can provide.
Following a resonant tank with transformers provides galvanic
isolation which is important for level conversion as well as for
safety. In certain applications, galvanic isolation is required for
proper operation. Resonant converters also have inherent
properties, such as soft switching of the semiconductor switches,
which lead to high efficiency and low noise.
[0004] The developing trends of the isolated DC-DC converters are
very high efficient, high power density and low cost. The resonant
DC-DC converters are suitable technology to achieve high efficiency
in power converters due to the intrinsic capability to achieve soft
switching (i.e., zero voltage switching (ZVS) and zero current
switching (ZCS)). It is also possible to increase the switching
frequencies in order to reduce the size of the reactive components
of the system.
[0005] However, there are still drawbacks regarding the
conventional three-phase resonant converter operating at high
frequency (HF). Galvanic isolation in three-phase converters poses
challenges in the construction and the connection types of the
three-phase resonant converter. The common transformer and
transformer connections types for the three-phase resonant
converter are three winding transformers. The cost of this existing
technology increases with attempts at higher efficiency and reduced
volume and weight.
[0006] Accordingly, it would be desirable to provide a DC-DC
converter topology that addresses at least some of the problems
identified above.
SUMMARY
[0007] It is an object of the present application to provide
improved resonant DC to DC converter topologies that can deliver
better efficiency and lower noise from smaller packages. This
object is solved by the subject matter of the independent claims.
Further advantageous modifications can be found in the dependent
claims.
[0008] According to a first aspect of the present application the
above and further objects and advantages are obtained by a
transformer circuit that includes a first transformer and a second
transformer, a first terminal of the first transformer connected to
a first terminal of the second transformer, and an inductor
connected between a second terminal of the first transformer and a
second terminal of the second transformer. The aspects of the
disclosed embodiments provide a topological circuit for a
three-phase DC-DC converter with a reduced number of transformers
or transformer windings. This allows for a simplified and more
efficient layout of the converter due to the reduction in
transformer windings.
[0009] In a first possible implementation form of the transformer
circuit according to the first aspect as such the transformer
circuit includes a primary side of three connections points
configured to receive a three-phase power input, the primary side
comprising a first input node formed by a connection of the second
terminal of the first transformer and a first terminal of the
inductor, a second input node formed by the connection of the first
terminal of the first transformer and the first terminal of the
second transformer and a third input node formed by a connection of
the second terminal of the second transformer and a second terminal
of the inductor. This implementation form provides a two-winding
transformer for a three-phase resonant converter.
[0010] In a second possible implementation form of the transformer
circuit according to the first aspect as such or according to the
first possible implementation form of the first aspect the first
input node is configured to receive a first phase of the
three-phase power input, the second node is configured to receive a
second phase of the three-phase power input and the third node is
configured to receive a third phase of the three-phase power input.
This implementation form provides a two-winding transformer for a
three-phase resonant converter.
[0011] In a third possible implementation form of the transformer
circuit according to the first aspect as such or according to any
one of the preceding possible implementation forms of the first
aspect the primary side of the transformer circuit is configured to
be connected to a resonant tank circuit to receive the three-phase
power input. This implementation form provides a two-winding
transformer for a three-phase resonant converter.
[0012] In a fourth possible implementation form of the transformer
circuit according to the third possible implementation form of the
first aspect as such the first input node is configured to be
connected to a first branch of the resonant tank circuit to receive
the first phase of the three-phase power input, the second input
node is configured to be connected to a second branch of the
resonant tank circuit to receive the second phase of the
three-phase power input and the third input node is connected to a
third branch of the resonant tank circuit to receive the third
phase of the three-phase power input. This implementation form
provides a two-winding transformer for a three-phase resonant
converter, which simplifies the construction and layout of the
converter.
[0013] In a fifth possible implementation form of the transformer
circuit according to the first aspect as such or according to any
one of the preceding possible implementation forms of the first
aspect the transformer circuit includes a secondary side configured
to deliver a three-phase power output, the secondary side
comprising a first output node formed by a third terminal of the
first transformer, a second output node formed by a connection of a
fourth terminal of the first transformer and a fourth terminal of
the second transformer, and a third output node formed by a third
terminal of the second transformer. The two-transformer topological
circuit for a resonant converter provides a three-phase power
output with greater efficiency than can be achieved with
three-transformer circuits.
[0014] In a sixth possible implementation form of the transformer
circuit according to the fifth possible implementation form of the
first aspect as such the secondary side is configured to be
connected to a three-phase rectifier circuit to deliver the
three-phase power output, the first output node being configured to
be connected to a first branch of the rectifier circuit, the second
output node being configured to be connected to a second branch of
the rectifier circuit and the third output node being configured to
be connected to a third branch of the rectifier circuit. The
two-transformer topological circuit for a resonant converter
provides a three-phase power output with greater efficiency than
can be achieved with three-transformer circuits.
[0015] According to a second aspect of the present application the
above and further objects and advantages are obtained by a resonant
converter circuit that includes a resonant tank circuit, and a
transformer circuit according to the first aspect or any one of the
first through seventh possible implementation forms of the first
aspect, wherein a resonant tank circuit is connected to a primary
side of the transformer circuit. The aspects of the disclosed
embodiments provide a resonant converter that includes a
transformer circuit with only two transformer windings. The reduced
number of windings lowers the volume of the resonant converter, as
well as lowering weight and cost while providing higher efficiency
and reliability.
[0016] In a first possible implementation form of the second aspect
as such, the resonant tank circuit comprises a first branch, a
second branch and a third branch, wherein the first branch is
configured to be connected to the first input node of the
transformer circuit, the second branch is configured to be
connected to the second input node of the transformer circuit, and
the third branch is configured to be connected to the third input
node of the transformer circuit. The aspects of the disclosed
embodiments provide resonant converter that is configured for
three-phase and includes a transformer circuit with only two
transformer windings. The reduced number of windings lowers the
volume of the converter, as well as weight and cost while providing
higher efficiency and reliability.
[0017] In a second possible implementation form of the second
aspect as such or according to the first possible implementation
form of the second aspect the first branch is configured to be
connected between a first input node of the resonant tank circuit
and the first input node of the transformer circuit, the second
branch is configured to be connected between a second input node of
the resonant tank circuit and the input node of the transformer
circuit, and the third branch is configured to be connected between
a third input node of the resonant tank circuit and the third input
node of the transformer circuit. The aspects of the disclosed
embodiments provide a three-phase resonant converter with a
transformer circuit that has only two transformer windings. The
reduced number of windings lowers the volume of the converter, as
well as weight and cost while providing higher efficiency and
reliability.
[0018] In a third possible implementation form of the second aspect
as such, or according to any one of the preceding possible
implementation forms of the second aspect, the first branch
comprises a first branch inductor connected in series with a first
branch capacitor, a first end of the first branch is configured to
be connected to the first node of the transformer circuit, the
second branch comprises a second branch inductor connected in
series with a second branch capacitor, a first end of the second
branch is configured to be connected to the second node of the
transformer circuit, and the third branch comprises a third branch
inductor connected in series with a third branch capacitor, a first
end of the third branch is configured to be connected to the third
node of the transformer circuit. The resonant converter of the
disclosed embodiments includes a two-winding transformer circuit
that is configured to connect to each branch of a three-phase
resonant tank circuit to provide a three-phase power output.
[0019] According to a third aspect of the present application the
above and further objects and advantages are obtained by a
three-phase resonant DC-DC converter system that includes a primary
side, a secondary side and a transformer circuit according to any
one of the preceding aspects and possible implementation forms
connected between the primary side and the secondary side. The
aspects of the disclosed embodiments provide a three-phase resonant
converter with a transformer circuit that includes only two
transformer windings. The reduced number of windings in the
transformer circuit lowers the volume, weight and cost of the
converter system, while providing higher efficiency and
reliability.
[0020] In a first possible implementation form of the three-phase
resonant DC-DC converter system according to the third aspect as
such the primary side comprises a DC voltage input circuit
configured to receive a DC input voltage, a resonant tank circuit
configured to be connected to the transformer circuit to provide
the three-phase power input to the transformer circuit and a
switching circuit connected between the DC voltage input circuit
and the resonant tank circuit. The resonant converter system of the
disclosed embodiments can be applied to any three-phase topological
circuit.
[0021] In a second possible implementation of the three-phase
resonant DC-DC converter system according to third aspect as such,
or according to the first possible implementation form of the third
aspect, the secondary side comprises a three-phase rectification
circuit connected between the transformer circuit and a DC voltage
output circuit, the rectification circuit configured to receive the
three-phase power output signal from the transformer circuit. The
resonant converter system of the disclosed embodiments can be
applied to any three-phase topological circuit to provide a
three-phase power output.
[0022] In a third possible implementation form of the three-phase
resonant DC-DC converter system according to the third aspect as
such or according to any one of the preceding possible
implementation forms of the third aspect the switching circuit is a
multi-level three-phase switching converter. The resonant converter
system of the disclosed embodiments can be implemented in any
suitable three-phase topological circuit including high-voltage
applications.
[0023] In a fourth possible implementation form of the three-phase
resonant DC-DC converter system according to the third aspect as
such or according to any one of the preceding possible
implementation forms of the third aspect the switches in the
switching circuit and switches in the rectification circuit
comprise gallium-nitride (GaN) transistors. The use of GaN devices
increases efficiency at a reduced cost.
[0024] These and other aspects, implementation forms, and
advantages of the exemplary embodiments will become apparent from
the embodiments described herein considered in conjunction with the
accompanying drawings. It is to be understood, however, that the
description and drawings are designed solely for purposes of
illustration and not as a definition of the limits of the disclosed
application, for which reference should be made to the appended
claims. Additional aspects and advantages of the application will
be set forth in the description that follows, and in part will be
obvious from the description, or may be learned by practice of the
application. Moreover, the aspects and advantages of the
application may be realized and obtained by means of the
instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In the following detailed portion of the present disclosure,
the application will be explained in more detail with reference to
the example embodiments shown in the drawings.
[0026] FIG. 1 is a block diagram illustrating an exemplary
three-phase DC-DC resonant converter system incorporating aspects
of the disclosed embodiments.
[0027] FIG. 2 illustrates a schematic diagram of an exemplary
transformer circuit incorporating aspects of the disclosed
embodiments.
[0028] FIG. 3 illustrates a schematic diagram of an exemplary
three-phase DC-DC resonant converter circuit incorporating aspects
of the disclosed embodiments.
[0029] FIG. 4 illustrates a schematic diagram of an exemplary
three-phase DC-DC resonant converter system incorporating aspects
of the disclosed embodiments.
[0030] FIG. 5 illustrates a schematic diagram an exemplary
three-phase DC-DC resonant converter system incorporating aspects
of the disclosed embodiments.
[0031] FIG. 6 illustrates a graph showing voltage gain
characteristics for a resonant circuit incorporating aspects of the
disclosed embodiments.
[0032] FIG. 7 illustrates an exemplary multi-level three-phase
DC-DC resonant converter system incorporating aspects of the
disclosed embodiments.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS
[0033] Referring to FIG. 1 there can be seen an exemplary block
diagram of a DC-DC three-phase resonant converter system 300
incorporating aspects of the disclosed embodiments. As shown in
FIG. 1, the DC-DC three-phase resonant converter system 300
generally includes an input circuit or primary side 302, and an
output circuit or secondary side 304. The primary side 302
generally comprises a DC voltage input circuit 30, an inverter
circuit 20 and a resonant tank circuit 10. The secondary side 304
generally includes a rectification circuit 40 and a DC output
voltage circuit 50. A transformer circuit 100 is connected between
the primary side 302 and the secondary side 304. The aspects of the
disclosed embodiments are directed to a topological circuit of a
three-phase DC-DC resonant converter system 300 that includes a two
winding HF transformer connection rather than the typical three
winding transformer connection. Reducing the number of transformer
windings, lowers the volume, weight and cost of the converter. The
construction and layout of the converter system 300 is simplified,
and the efficiency of the system 300 is improved.
[0034] FIG. 2 illustrates a schematic block diagram of an exemplary
transformer circuit 100 incorporating aspects of the disclosed
embodiments. The transformer circuit 100 is a two-winding HF
transformer circuit that is suitable for a high efficiency, high
power density and low cost DC-DC converter in any application that
requires galvanic isolation and independence between the input
voltage value and the output voltage value of the converter
system.
[0035] The transformer circuit 100 of the disclosed embodiments
includes two HF transformers T1 and T2. The transformers T1 and T2
can comprise two single transformers. Alternatively, the
transformers T1 and T2 can be integrated in one single core, which
can be referred to as a two winding transformer. In one embodiment,
the transformers T1 and T2 are HF transformers with a turns ratio
of n:1. For the purposes of the disclosure herein, the two
transformers, or transformer windings, will be referred to as
transformers T1 and T2.
[0036] As shown in FIG. 2, a first terminal TI-1 of the first
transformer T1 is connected to a first terminal T2-1 of the second
transformer T2. An inductor L1 is connected between a second
terminal T1-2 of the first transformer T1 and a second terminal
T2-2 of the second transformer T2.
[0037] The primary side of the transformer circuit 100 shown in
FIG. 2 includes three connection points or nodes 101, 102 and 103.
The first connection point 101, also referred to as the first input
node 101, is formed by the connection of the second terminal T1-2
of the first transformer T1 and a first terminal L1-1 of the
inductor L1. A second connection point or input node 102 is firmed
by the connection of the first terminal T1-1 of the first
transformer T1 and the first terminal T2-1 of the second
transformer T2. The third connection point or input node 103 is
formed by the connection of the second terminal T2-2 of the second
transformer T2 and the second terminal L1-2 of the inductor L1. The
first, second and third input nodes 101, 102 and 103, are
configured to receive the first, second and third phases,
respectively, of a three-phase input power.
[0038] In one embodiment, the primary side of the transformer
circuit 100 is configured to be connected to a resonant tank
circuit, such as the resonant tank circuit 10 illustrated in FIG.
1. In the examples of FIGS. 1, 3 and 4, and as will be described
further below, the resonant tank circuit 10 is a three-phase
resonant tank circuit.
[0039] Referring to FIGS. 3 and 4, in one embodiment, the first
input node 101 on the primary side of the transformer circuit 100
is configured to be connected to a first branch RT.sub.1 of the
resonant tank circuit 10. The second input node 102 on the primary
side of the transformer circuit 100 is configured to be connected
to a second branch RT.sub.2 of the resonant tank circuit 10. The
third input node 103 on the primary side of the transformer circuit
100 is configured to he connected to a third branch RT.sub.3 of the
resonant tank circuit 10. The first, second and third branches
RT.sub.1, RT.sub.2 and RT.sub.3 are connected to different phases
of the three-phase power input.
[0040] The transformer circuit 100 shown in FIG. 2 includes a
secondary side comprising three connection points or output nodes
121, 122 and 123. The secondary side of the transformer circuit 100
is configured to deliver a three-phase power output.
[0041] In one embodiment, the first output node 121 is formed by a
third terminal T1-3 of the first transformer T1. The second output
node 122 is formed by a connection of a fourth terminal T1-4 of the
first transformer T1 and a fourth terminal T2-4 of the second
transformer T2. The third output node 123 is formed by a third
terminal T2-3 of the second transformer T2.
[0042] The output nodes 121, 122 and 123 of the secondary side of
the transformer circuit 100 is configured to be connected to a
rectifier circuit, such as the three-phase rectifier circuit 40
shown in FIGS. 1 and 4. In this example, the first output node 121
is configured to be connected to first branch 41 of the rectifier
circuit 40. The second output node 122 is configured to be
connected to a second branch 42 of the rectifier and the third
output node 123 is configured to be connected to a third branch 43
of the rectifier circuit 40.
[0043] The resonant converter system 300 shown in FIG. 1 includes a
resonant converter circuit 200. The resonant converter circuit 200
generally comprises a resonant tank circuit 10 and the transformer
circuit 100. In one embodiment, as illustrated for example in FIGS.
3 and 4, the resonant tank circuit 10 is connected to the nodes
101, 102 and 103 on the primary side of the transformer circuit
100. The resonant tank circuit 10 can be configured to contain a
single or multi-resonant tank in each phase.
[0044] The first branch RT.sub.1 of the resonant tank circuit 10 is
connected between a first input node 111 of the inverter circuit 20
and the first input node 101 of the transformer circuit 100. The
second branch RT.sub.2 of the resonant tank circuit 10 is connected
between a second input node 112 of the inverter circuit 20 and the
second input node 102 of the transformer circuit 100. The third
branch RT.sub.3 of the resonant tank circuit 10 is connected
between the third input node 113 of the inverter circuit 20 and the
third input node 103 of the transformer circuit 100.
[0045] As is illustrated in FIG. 4, the resonant tank circuit 10
generally comprises an LLC type resonant tank and includes
inductors L.sub.ra, L.sub.rb and L.sub.rc in each branch RT.sub.1,
RT.sub.2 and RT.sub.3, respectively. The inductors L.sub.ra,
L.sub.rb, L.sub.rc in each branch or phase are followed by a
respective capacitor C.sub.ra, C.sub.rb and C.sub.rc. The inductors
L.sub.ra, L.sub.rb and L.sub.rc are the resonant inductors and can
be constructed with independent cores or integrated in one single
core. The capacitors C.sub.ra, C.sub.rb and C.sub.rc are the
resonant capacitors.
[0046] In one embodiment, the first branch RT.sub.1 of the resonant
tank circuit 10 comprises the inductor L.sub.ra connected in series
with the capacitor C.sub.ra. A first end RT.sub.1-1 of the first
branch RT.sub.1 is configured to be connected to the first node 101
of the transformer circuit 100. A first terminal of the capacitor
C.sub.ra forms the first end RT.sub.1-1 in this example. A first
terminal of the inductor L.sub.ra forms the second end RT.sub.1-2
of the first branch RT.sub.1 and is connected to the first input
node 111 of the inverter circuit 20.
[0047] The second branch RT2 of the resonant tank circuit 10
comprises the inductor L.sub.rb connected in series with the
capacitor C.sub.rb. A first end RT.sub.2-1 of the second branch
RT.sub.2 is configured to be connected to the second node 102 of
the transformer circuit 100. A first terminal of the capacitor
C.sub.rb forms the first end RT.sub.2-1 in this example. A first
terminal of the inductor L.sub.rb firms the second end RT.sub.2-2
of the second branch RT.sub.2 and is connected to the second input
node 112 of the inverter circuit 20.
[0048] The third branch RT3 of the of the resonant tank circuit 10
comprises the inductor L.sub.rc connected in series with the
capacitor C.sub.rc. A first end RT.sub.3-1 of the third branch
RT.sub.3 is configured to be connected to the third node 103 of the
transformer circuit 100. A first terminal of the capacitor C.sub.rc
forms the first end RT.sub.3-1 in this example. A first terminal of
the inductor L.sub.rc forms the third end RT.sub.3-2 of the third
branch RT.sub.3 and is connected to the third input node 113 of the
inverter circuit 20.
[0049] FIG. 4 is a schematic diagram of a three-phase resonant
DC-DC converter system 300 incorporating aspects of the disclosed
embodiments. The three-phase resonant DC-DC converter 300 is
configured to receive a DC power V.sub.in and create a three-phase
alternating current (AC) power appropriate for driving the resonant
converter circuit 200. The inverter or switching circuit 20 is
configured to receive the DC input power V.sub.in from the DC
voltage input circuit 30 across positive (+) and negative (-) input
rails P, N. An input capacitor C.sub.in is coupled across the input
rails P, N and provides filtering of the DC input power
V.sub.in.
[0050] In the example of FIG. 4, the inverter circuit 20 includes
three half bridge circuits 21, 22, 23 are coupled in parallel
across the DC input power V.sub.in and may be operated to produce a
three-phase power at three output nodes 111, 112, 113. Each half
bridge circuit 21, 22, 23 includes a pair of switches, S.sub.p1,
S.sub.p2; S.sub.p3, S.sub.p4; and S.sub.p5, S.sub.p6, respectively.
Each switch S.sub.p1, S.sub.p2, S.sub.p3, S.sub.p4, S.sub.p5,
S.sub.p6 is configured to be operated, i.e. turned on or off, by a
switch control signal (not shown). These pairs of switches allow
the input nodes 111, 112, 113 to be alternately coupled to the
positive input rail P or to the negative input rail N to create an
AC power signal at the corresponding output node 121, 122, 123, as
is generally understood.
[0051] The switches S.sub.p1, S.sub.p2, S.sub.p3, S.sub.p4,
S.sub.p5, and S.sub.p6 can be any suitable type of transistors,
such as for example, metal-oxide-semiconductor
field-effect-transistors, (MOSFET), insulated gate bipolar
transistor (IGBT), GaN High Electron Mobility transistors
(GaN-HEMT), and metal-oxide-semiconductor-controlled thyristor
(MCT). The semiconductor material of the devices can be based on
silicon (Si), silicon-carbide (SiC), GaN as well as other
semiconductor materials, or any combination thereof.
[0052] The resonant converter 200 is followed by the three-phase
rectifying bridge cell or circuit 40 that is configured to receive
a three-phase AC power and produce a DC output power V.sub.o. The
exemplary rectifier circuit 40 receives a three-phase AC power at
the three rectifier circuit 40 input nodes 121, 122, 123. The
three-phase AC input power in this example is produced by the
resonant circuit 200.
[0053] The DC output voltage circuit 50 includes a positive (+)
output rail H and a negative (-) output rail L for the DC output
power V.sub.o. An output filter capacitor C, is coupled across the
positive (+) and negative (-) output rails H, L and is configured
to filter noise and reduce ripple from the output power
V.sub.o.
[0054] Three half bridge circuits 41, 42, 43 are coupled in
parallel across the output rails H. L. Each half bridge circuit 41,
42, 43 is configured to receive one phase of the three-phase AC
power at a center or input node 121, 122, 123 of each half bridge
circuit 41, 42, 43 respectively.
[0055] Each half bridge circuit 41, 42, 43 uses a pair of switches
S.sub.s1, S.sub.s2; S.sub.s3, S.sub.s4; and S.sub.s5, S.sub.s6,
respectively to rectify the three-phase AC power from the resonant
converter 200. As with switches S.sub.p1, S.sub.p2, S.sub.p3,
S.sub.p4, S.sub.p5, S.sub.p6 on the primary side of the converter
system 300, the switches S.sub.s1, S.sub.s2, S.sub.s3, S.sub.s4,
S.sub.s5, and S.sub.s6 may be any appropriate type of switching
device configured to conduct, or not conduct, electric current
based on switch control signals. If synchronous rectification (SR)
is not implemented, the switches can comprise diodes.
[0056] FIG. 5 illustrates one embodiment of a resonant converter
system incorporating aspects of the disclosed embodiments. In this
example, the switches S.sub.p1, S.sub.p2, S.sub.p3, S.sub.p4,
S.sub.p5, S.sub.p6 of the inverter circuit 420 on the primary side
of the converter system and the switches S.sub.s1, S.sub.s2,
S.sub.s3, S.sub.s4, S.sub.s5, S.sub.s6 of the rectifier circuit 440
on the secondary side of the converter system are wide band
GaN-HEMT transistors.
[0057] FIG. 6 illustrates exemplary voltage gain characteristics
for different quality factors of a three-phase resonant DC-DC
converter system 300 incorporating aspects of the disclosed
embodiments. The DC output voltage V.sub.o in volts (V) is
presented along the Y-axis while the frequency fin kilohertz (kHz)
is presented along the X-axis. As can be seen from the graphs, the
natural resonance frequency f.sub.res is similar to the LLC type
resonant converter.
[0058] The two-transformer, three-phase resonant DC-DC converter
300 of the disclosed embodiments is suitable for any application
that requires galvanic isolation and independence of the voltage
value in the output of the system. FIG. 7 illustrates one
embodiment of a two-transformer, three-phase resonant converter
system 500 for a high voltage application. In this example, the
resonant converter system 500 is a multi-level converter. The
primary side 502 of the resonant converter system 500 includes a
multi-level inverter circuit 520.
[0059] In this example, the inverter circuit 520 includes pairs of
switches S.sub.p1, S.sub.p2; S.sub.p3, S.sub.p4; and S.sub.p5,
S.sub.p6 that are connected in series with each other and a
capacitor bank of series connected capacitors C.sub.1, C.sub.2 and
C.sub.3 is connected between the positive rail P and the negative
rail N. A first terminal of capacitor C.sub.1 is connected to the
positive rail P and a first terminal of switch S.sub.p1. A second
terminal of capacitor C.sub.1 is connected to a first terminal of
capacitor C.sub.2, a second terminal of switch S.sub.p2 and a first
terminal of switch S.sub.p3. The second terminal of switch S.sub.p1
is connected to the first terminal of switch S.sub.p2 and the
connection forms output node 111. The output node 111 is connected
to the first branch RT.sub.1 of the resonant tank 10.
[0060] The second terminal of capacitor C.sub.2 is connected to the
second terminal of switch S.sub.p4, the first terminal of capacitor
C.sub.3 and the first terminal of switch S.sub.p5. The second
terminal of switch S.sub.p3 is connected to the first terminal of
switch S.sub.p4 and forms output node 112. Node 112 is connected to
the second branch RT.sub.2 of the resonant tank 10.
[0061] The second terminal of capacitor C.sub.3 is connected to the
negative rail N and the second terminal of switch S.sub.p6. The
second terminal of switch S.sub.p5 is connected to the first
terminal of switch S.sub.p6 and the connection form output node
113. Node 113 is connected to the third branch RT.sub.3 of the
resonant tank 10.
[0062] Each switch S.sub.p1, S.sub.p2, S.sub.p3, S.sub.p4,
S.sub.p5, S.sub.p6 is configured to be operated, i.e. turned on or
off, by a switch control signal to produce the three-phase power
suitable to drive the resonant converter circuit 200. In one
embodiment, the switching pattern of the control signals is phase
shifted 120 degrees among each half-bridge leg 521, 522, 523 of the
inverter circuit 520. In this example, the switches S.sub.p1,
S.sub.p2, S.sub.p3, S.sub.p4, S.sub.p5, S.sub.p6 in the inverter
circuit 520 on the primary side 502 and the switches S.sub.s1,
S.sub.s2, S.sub.s3, S.sub.s4, S.sub.s5, S.sub.s6 in the rectifier
circuit 540 on the secondary side 504 are wide band GaN-HEMT
transistors. In alternate embodiments, the resonant converter
system 500 can include any suitable switch types other than
including wide band GaN-HEMT transistors.
[0063] The aspects of the disclosed embodiments are directed to a
two-transformer, three-phase resonant DC-DC converter. The
two-transformer circuit of the disclosed embodiments reduces the
number of transformer windings, which results in a reduction in
volume, weight and cost. The reliability of the resonant converter
is increased, due to less losses in the transformer, which also
eases the management of heat in the transformer. The number of
capacitors needed for the input and output filters of the resonant
converter is reduced, which also results in a reduction in volume,
weight and cost. The inductors of the resonant tank can be
integrated with each other into one single core. This topology
results in a simplified and more efficient layout of the resonant
converter components.
[0064] The voltage gain characteristic of the resonant converter of
the disclosed embodiments is greater than one. This enables boost
and buck modes of operation. Additionally, storage elements are not
needed in order to achieve ZVS on the primary side of the resonant
converter and ZCS on the secondary side of the resonant
converter.
[0065] The resonant converter of the disclosed embodiments is
suitable for any application that requires galvanic isolation and
independence of the voltage value in the output of the system.
Exemplary implementations include energy flow management for
telecom power supplies. The two-transformer circuit of the
disclosed embodiments can be applied to any three-phase topological
circuit, including resonant and pulse wave modulated circuits. The
circuits can be implemented for any power level as there is no
inherent limitation in the topological circuits itself. The
circuits can be extended for any number of converters and different
kinds of connections (serial/parallel). A primary characteristic of
the two-transformer, three-phase resonant converter circuit of the
disclosed embodiments is that it can operate as a LLC type resonant
converter.
[0066] Thus, while there have been shown, described and pointed
out, fundamental novel features of the application as applied to
the exemplary embodiments thereof, it will be understood that
various omissions, substitutions and changes in the form and
details of devices and methods illustrated, and in their operation,
may be made by those skilled in the art without departing from the
spirit and scope of the presently disclosed application. Further,
it is expressly intended that all combinations of those elements,
which perform substantially the same function in substantially the
same way to achieve the same results, are within the scope of the
application. Moreover, it should be recognized that structures
and/or elements shown and/or described in connection with any
disclosed form or embodiment of the application may be incorporated
in any other disclosed or described or suggested form or embodiment
as a general matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
* * * * *